64561540 has 48 divisors (see below), whose sum is σ = 141346800. Its totient is φ = 24740352.

The previous prime is 64561537. The next prime is 64561543. The reversal of 64561540 is 4516546.

It is an interprime number because it is at equal distance from previous prime (64561537) and next prime (64561543).

It can be written as a sum of positive squares in 8 ways, for example, as 8491396 + 56070144 = 2914^2 + 7488^2 .

It is not an unprimeable number, because it can be changed into a prime (64561543) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 90706 + ... + 91414.

It is an arithmetic number, because the mean of its divisors is an integer number (2944725).

Almost surely, 2^64561540 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 64561540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (70673400).

64561540 is an abundant number, since it is smaller than the sum of its proper divisors (76785260).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

64561540 is a wasteful number, since it uses less digits than its factorization.

64561540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 904 (or 902 counting only the distinct ones).

The product of its (nonzero) digits is 14400, while the sum is 31.

The square root of 64561540 is about 8035.0196017185. The cubic root of 64561540 is about 401.1664700624.

The spelling of 64561540 in words is "sixty-four million, five hundred sixty-one thousand, five hundred forty".